Pure fluid device

ABSTRACT

A pure fluid device for providing efficient digital operation. A laminar input stream is caused to interact with one or more control streams within a confined interaction chamber to provide a binary output pressure whose level depends upon the laminar or turbulent condition of flow within the chamber. The invention provides extremely rapid switching in a precisely controllable manner. The invention is also operable to provide controllable proportional amplification by producing an output pressure of a magnitude variable in response to control pressure variation.

United States Patent 1 3,667,489

Blaiklock et a1. [45] June 6, 1972 [54] PURE FLUID DEVICE 3,469,5939/1969 O'Keefe ..l37/81.5

172] Inventors: Paul M. Blaiklock, Newton Centre; Hansggti Diem KhmerDuxbury bmh Mass 3:51 1:256 5/1970 Ab1er.:::::::::::: .:::137/81:5

[73] Assignee: Fluidic Industries, Inc., l-lingham, Mass.

[22] Filed: Jan. 12, 1970 21 Appl. No.: 2,297

52 us. Cl ..137 s1.s

[51] Int. Cl. ..Fl5c 1/18 [58] Field ofSearchm; ..l37/8l.5;235/20l [56]References Cited UNITED STATES PATENTS 7 3,187,763 6/1965 Adams..l37/8l.5 3,272,214 9/1966 Warren.. ...,137/8l.5 3,362,421 1/1968Schaffer.... ....l37/81.5 3,452,767 7/1969 Posmgies ..137/81.5

Primary Examiner-Samuel Scott Attorney-Joseph Weingarten [57] ABSTRACT Apure fluid device for providing efficient digital operation. A laminarinput stream is caused to interact with one or more control streamswithin a confined interaction chamber to provide a binary outputpressure whose level depends upon the laminar or turbulent condition offlow within the chamber. The invention provides extremely rapidswitching in a precisely controllable manner. The invention is alsooperable to provide controllable proportional amplification by producingan output pressure of a magnitude variable in response to controlpressure variation.

8 Claims, 13 Drawing Figures PATENTEDJUN 6 1912 SHEET 1 BF 4 FIG. I

PRIOR ART DEVICE INVENTORS 6H PAUL M. BLAlKlfilglg I y ANs-D| K1 '2CONTROL PRESSURE (INS. OF WATER) ATTOR EYS Amm. m0 wz: mmDmwmma PDnZbO11 r 4 i i PATENTEDJUH s 1972 3, 67, 489

SHEET 2 or 4 I04 2 I04 I07 I05 I07 FIG. 4A FIG. 4B 8 v E J LL] 5 g U) zI 5 28 FIG. 9 E CL D O. D O

-o.5 00 0.5 lb H5 2b CONTROL PRESSURE INVENTORS (INS. OF WATER) PAUL M.BLAIKLOCK BY HANS-DI R K|NNER ATTOR YS PATENTEDJUN 5 I972 SHEET 3 OF 4-j INVENTORS PAUL-M. BLAIKLOCK H Wm K 2%,.

ATTOR EYS INNER PATENTEUJUN 6 I972 3.667, 489

sum 0F 4 OUTPUT PRESSURE (INS. OF WATER) ix CONTROL PRESSURE (ms. OFWATER) SET INPUTS OOI I T OUTPUT INVENTORS PAUL M. BLAIKLOCK BY HANS-DITER KINNER ATTORN YS FIG. I2

PURE FLUID DEVICE FIELD OF THE INVENTION This invention relates tofluidic devices and more particularly to pure fluid devices employinglaminar flow.

BACKGROUND OF THE INVENTION Pure fluid devices are known in which fluidstreams are employed for control purposes in many applications. Suchdevices can be incorporated into networks and systems much like theirelectronic counterparts to provide intended indication, control andlogic functions. One class of pure fluid devices, utilizes thecontrolled interaction of a control stream and a laminar fluid powerstream to provide pneumatic control without moving parts. In general, alaminar fluid power stream is directed from the orifice of a supply tubethrough an unconfined space toward the orifice of a collector tube, witha control tube arranged in the unconfined space and adapted to ,direct acontrol stream into interaction with the power stream.

In the absence of a control stream, the power stream reaches thecollector tube in a laminar condition. When, however, the control streamis applied with predetermined flow to the power stream, the power streamchanges from a laminar t turbulent condition, with the result that thepressure in the collector tube is reduced from that existing underlaminar flow conditions. The difference in pressure in the collectortube can be employed to represent binary device states for digitalcontrol purposes. Moreover, the change in pressure in the collector tubecaused by the change in the power stream from laminar to turbulent flowcan be greater than the change in pressure applied to the control streamto effect alteration of the power stream flow condition, and, thus,amplification can be provided.

However, devices of known construction do not ofier predictable orprecisely controllable operation sufficient for many purposes. Forexample, when employed to provide proportional amplification,conventional turbulence amplifiers require extremely critical control ofthe pressure of the control stream to achieve intended pressurevariation in the device output, such critical control not being usuallyachievable in practical operating environments. This same deficiency ofcontrol precision also causes unreliable and often imprecise digitaldevice operation, thereby limiting the utility of such conventionaldevices in fluidic logic systems.

SUMMARY OF THE INVENTION In accordance with the present invention a purefluid device is provided in which efficient and precisely controllabledigital operation is achieved, in addition to controllable proportionalamplification. The invention utilizes the transition from a laminar flowcondition to one of turbulent flow and accomplishes such transition bymeans of a shaped confined interaction chamber which is effective topermit improved device operation.

In brief, the novel device includes an input passage or tube adapted toestablish and maintain laminar flow and communicating with a shapedconfined interaction chamber which, in turn, communicates with ashielded region vented to the working atmosphere. The use of a laminarflow stream provides a considerable advantage over conventionalturbulence devices. For example, the invention utilizes very low inputand control pressures and does not exhibit any appreciable suction as inturbulence devices. One or more control passages are coupled to theinteraction chamber and each is operative to direct a low energy controlstream into intersection with a laminar input stream flowingtherethrough. An output passage is disposed on a common axis with theinput passage and communicates with the open region. In the absence of acontrol stream, the input stream flows laminarly through the interactionchamber and the adjacent shielded region to the output passage, givingrise to a relatively high output pressure therein. When a control streamis directed into intersecu'on with the laminar input stream, the inputstream undergoes a transition from a laminar to a turbulent state,resulting in a predetermined decrease in output pressure. The relativelyhigher and lower output pressures can provide intended binary outputstates.

The invention is operative in either of two modes of operation, one modeproviding effective binary operation, while theother mode providesimproved linear amplification. For binary operation, the shapedinteraction chamber includes means for providing fluid feedback thereinin a manner operative to achieve extremely rapid switching from onestate to another. For linear operation, such feedback means are notnecessary and the confined interaction chamber provides a controlledlaminar jet deflection and distortion to achieve markedly improvedamplifier operation.

DESCRIPTION OF THE DRAMNGS The invention will be more fully understoodfrom the following detailed description, taken in conjunction with theaccompanying drawings, in which:

FIG. 1 is a plan view of a fluid device embodying the invention;

FIG. 2 is a sectional elevation view of the embodiment of FIG. 1;

FIG. 3 is a plot of output pressure versus control pressure useful incomparing digital operation of the invention and operation of a priorart turbulence amplifier;

FIGS. 4A and 4B are sectional elevational views of alternativeimplementations of the embodiment of FIG. 1;

FIG. 5 is a sectional elevation view of an alternative implementation ofthe device of FIG. 1;

FIG. 6 is a plan view of a portion of the device formed in plate 42 ofFIG. 4;

FIG. 7 is a plan view of a further embodiment of the invention;

FIG. 8 is a plot of output pressure versus control pressure useful inillustrating the proportional amplifier characteristics of theinvention, with a control jet applied via port 31a;

FIG. 9 is a partly cut-away plan view of an alternative implementationof the embodiment of FIG. 7;

FIG. 10 is a plot of output pressure versus control pressure useful inillustrating the proportional amplifier characteristics of theembodiment of FIG. 7, with a control jet applied via port 24;

FIG. 11 is a schematic representation of a flip-flop utilizing theinvention; and

FIG. 12 is a schematic representation of an AND gate utilizing theinvention.

DETAILED DESCRIPTION OF THE INVENTION A fluid device according to theinvention is illustrated in FIGS. 1 and 2 and includes an input tube 10having an orifice 25 communicating with a shaped confined interactionchamber which includes an interaction region 12 and a contiguous shapedregion 14. A collector or output tube 16 is disposed on a common axiswith input tube 10, the orifice 18 of output tube 16 communicating witha shielded region 20 which is vented to the working atmosphere. Region20 is shaped as illustrated to provide a large area vented zone; theparticular shape is not especially critical. The top and bottom walls 11and 13 of region 12 are substantially parallel and are coplanar withinput tube 10. That is, input tube 10 is of a diameter which is equal toand in alignment with walls 11, and 13, as seen in FIG. 2. The sidewalls 19 and 21 of region 12 are substantially parallel and areoutwardly disposed from tube ing from input tube through zone 12. In theillustrated embodiment, eight control tubes 22 are shown and some or allof these control tubes can be used for interconnecting other fluidicdevices to form predetermined logical network configurations, as will bedescribed. For many purposes only a single control tube is required, andof course the invention can be implemented with a single control tubefor these purposes.

A pair of ports 24 are disposed in communication with the input end ofinteraction zone 12 adjacent the input orifice 25 of input tube 10 andare operative to vent the interaction zone to prevent suction on thecontrol ports when the input stream is in turbulent condition. A port 29is provided for each control tube 22 for supply of fluid thereto, whilean output port 33 is provided for output tube 16 to couple the outputstream to utilization means. An input port (not shown) is provided tosupply fluid to input tube 10. The shaped region 14 includes side walls26 which flare outwardly from zone 12 and which continue at the sameflare angle to define the side walls 27 of zone 20. Region 14 includes achannel 28 in respective upper and lower walls 34 and 35 and havingsubstantially the same width as the width of zone 12 and which extendsalong the axis of the device to a point slightly less than the fulllength of region 14 to define a respective thin rib or knife edge 30. Asseen in FIG. 2, the walls 34 and 35 of region 14 are outwardly disposedand parallel to the respective walls 13 and 11 of region l2. Ribs 30have confronting surfaces which are removed from the planes of the walls11 and 13 by an amount to prevent interference with the laminar flow ofthe input stream in the absence of control pressure.

The invention is illustrated in greatly enlarged form, actual devicesbeing generally of rather small size. For example, a device of the typeshown in FIG. 1 typically has input and output tubes of 0.0l75 inchdiameter and an interaction chamber of 0.34 inch in length. The devicecan be fabricated for example by machining of etching individualelements into respective upper and lower plateswhich can be securedtogether to provide a completed fluid device therein. For example, thedevice according to the invention, as seen in FIG. 2, is formed withinfirst and second plates and 17 of metal or other suitable material. Thefluid tubes are usually configured of semicircular cross section in eachplate so that when the plates are secured together, a substantiallycircular cross section fluid tube is provided for efficient fluid flow.Alternatively a square fluid tube cross section can be employed. Thedevice configuration formed in each plate is identical, with theexception of the fluid supply ports and vents, which are usually formedin a single plate. For many purposes, a plurality of devices are formedas a single structure to provide a complete operational network orsystem.

Input tube 10 is of a length and diameter to establish and maintain afluid stream in laminar flow therein such that a laminar stream willemerge from orifice and flow through regions 12, 14 and 20 and bereceived by collector tube 16 substantially in laminar condition, in theabsence of any control stream applied by one or more control tubes 22.The laminar fluid stream touches the top and bottom walls 11 and 13 ofof region 12 as it flows therethrough. The control stream has a lesserflow and lesser pressure than the input stream and is usually in laminarflow. Typically, supply pressures of less than 1.5 psi and controlpressures of less than 0.1 psi are employed.

With application of a control stream from a control tube 22, the supplystream deflects and distorts by reason of the momentum of the controlflow and pressure build-up in the confined region 12. The distortedsupply stream flowing in region 14 engages the knife edges which act asa source of disturbance to cause the stream to rapidly become turbulent.The turbulent stream tends to reflect ofi knife edges 30 and recirculateback through channel 28 toward zone 12, this recirculation causing anavalanche or positive feedback effect which is operative to causetransition from laminar to turbulent flow in an extremely short timeinterval. The pressure within collector tube 16 drops markedly when thesupply stream becomes turbulent, this pressure drop indicating a changein the device state. The device thus acts in a binary manner to provideone of two output levels depending upon the presence or absence of acontrol jet which governs whether the fluid stream flow is laminar orturbulent.

It is a particular feature of the invention that the transition betweenlaminar and turbulent flow is achieved in an extremely short timeinterval. Moreover, the pressure in collector tube 16 when the supplystream is turbulent, is at a lower pressure than usually obtainable byconventional devices. Thus, the invention provides a fluid device havingmarkedly improved switching characteristics.

The switching performance of the invention is shown in the graph of FIG.3 in which the solid curve depicts the output pressure in the collectortube of the device as a function of control pressure in the controltube. It is evident that the output pressure remains substantiallyconstantuntil the controlv pressure is approximately 0.4 inches ofwater. A slight further increase in control pressure causes theindicated rapid decrease in output pressure, a minimum output pressureof 0.2 inches of water typically being achieved. It will be noted thatthe cut-off characteristics of the device are extremely sharp andrelatively low residual output pressure is achieved. In contrast, thedotted curve illustrates the typical response of a turbulence amplifierof conventional construction and it is seen that there is a relativelygradual variation in output pressure with relatively large changes incontrol pressure. As a result, such conventional devices exhibit poorcut-off characteristics and a generally higher minimum output pressure.

The rib or knife edge 30 is but one form of obstruction operative inaccordance with the principles of the invention to provide rapidswitching characteristics. In some instances, the obstruction providedat the downstream end of region 14 is alone sufiicient to provide theintended fluid feedback without channels 28. For example, a rib can beprovided across the full width of region 14.

Another example of an obstruction employed to accomplish intended deviceoperation is shown in FIG. 4A which is an end view of a device of thetype shown in FIG. 1 as viewed from region 20 toward input tube 10.Walls and 101 are disposed transversely of the device between regions 14and 20, with a slit 102 therebetween extending between the top andbottom walls and having a width approximately equal to the diameter oforifice 103 of input tube 10 and in alignment therewith. Vertical slits104 can also be provided adjacent the other ends of walls 100 and 101 toprovide suitable venting of region 14. A variation of the feedbackobstruction is illustrated in FIG. 4B and includes a square aperture 105formed in a tranversely disposed wall 106 and in alignment with orifice103 of the input tube 10. Vent slits 107 are provided as above. Inoperation, laminar stream flows through region 14 and, in the absence ofa control stream applied to one or more of the control tubes, thelaminar stream passes through the aperture provided in the transversewall, to be received by the output tube. Upon application of a controlstream, the laminar stream is deflected and/or distorted into impingingrelationship with the transverse wall, causing turbulence in the streamand causing recirculation of fluid back toward region 12. As a result ofthe fluid feedback, the laminar stream rapidly becomes turbulent therebycausing a correspondingly rapid decrease in output pressure in theoutput tube.

An alternative implementation of the invention is illustrated in FIGS. 5and 6 in which the novel device is constructed in four plates which canbe combined in a laminated package to form a complete device. The deviceconfiguration is as shown in FIG. 1 and is substantially symmetrical.For purposes of clarity only two plates are shown, the other two platesbeing substantially the same. As seen in FIG. 5, plate 40 has formedtherein half of supply tube 10 (FIG. 1) and half of collector tube 16.The semicircular portions of the orifices 21 of control tubes 22 areseen in the illustrated cross section. A similar tube configuration isformed in another plate (not shown) which is disposed in confrontingrelationship with plate 40 to provide the completed fluid tube structureand interaction zone 12. A plate 42 has formed therein the shaped region14 and is placed in contact with plate 40, as illustrated, together witha like pair of plates to form the device. A plan view of plate 42 isdepicted in FIG. 5 and includes the uniquely shaped region 14, region20, ports 25 which communicate with vents 24 formed within plate 40, andports 27 which provide inlet and outlet ports for the control tubes 22formed in plate 40.

The invention can also be employed in a slightly different configurationto provide improved proportional amplification. In this mode ofoperation, the shaped region 14 (FIG. 1) is not employed. As seen inFIG. 7, the novel device is-similar to the device of FIG. 1 except thatthe region 41 disposed between interaction zone 12 and output tube 16 isa shielded region which is vented to the working atmosphere. Forproportional operation, a pair of control tubes 22a are usuallyemployed, with each disposed on a respective opposite side ofinteraction zone 12, and coupled to respective control ports 31a forintroduction of a suitable supply of control fluid. The control tubes220 preferably communicate with interaction zone 12 at positions nearthe input orifice of supply tube 10.

The device in the illustrated configuration operates as a high gain lownoise proportional amplifier and exhibits a typical operatingcharacteristic as shown in FIG. 8. As described hereinabove, a supplystream is provided and maintained within supply tube in laminar flowcondition and the laminar stream flows through interaction region 12 andthence through zone 41 to the collector orifice 18 of output tube 16. Alow pressure control stream enters the communication region 12 via oneof control tubes 22a and causes deflection of the laminar stream flowingthrough region 12 by pressure build-up in the interaction region. Thelaminar stream is thereby deflected away from output orifice 18 causinga controlled decrease in output pressure which is proportionally relatedto the magnitude of the control pressure. By introducing a controlpressure to each control port 31a, deflection of the laminar stream canbe accomplished in an amount related to the difference between the twocontrol pressures.

As seen'in FIG. 8, the novel fluid amplifier provides an output pressurewhich is directly proportional to an applied control pressure and whichis precisely and controllably variable in response thereto. Relativelylarge changes in output pressure can thereby be provided in response torelatively small variations in control pressure. Conventional turbulenceamplifiers cannot be easily employed in many applications requiringcontrolled proportional amplification, since significant outputvariation, in addition to noise, occurs for extreme ly small changes incontrol pressure and a degree of control is required which is not easilyachievable in practice.

As an alternative implementation of the embodiment of FIG. 7, thecontrol tubes 220 can be eliminated, and control streams introduced intoregion 12 via ports 24. Of course in this embodiment, ports 24 would becoupled to a source of control pressure, rather than being vented as inthe embodiments described hereinbefore. Operation is substantially asdescribed above, wherein a pressure build-up within region 12, caused byapplication of a control stream, causes deflection of the laminar inputstream away from the side of increased pressure. Variation in outputpressure can be detected by a single output tube 16, as in FIG. 7, or bya pair of displaced output tubes 48 and 49, as in FIG. 9. Output tubes48 and 49 are disposed on respective opposite sides of the longitudinalaxis of the device along which the laminar stream flows, and are coupledto respective output ports 51. Proportional operation of the device ofFIG. 7 with the control, stream applied via port 24 is depicted in FIG.10. It should evident that high gain, low noise amplification isprovided.

stream, the input stream remaining substantially in laminar flow. Flowof the control stream on one side of interaction region 12 causes apressure build-up which in turn causes deflection of the laminar inputstream away from the region of increased pressure. A differential outputpressure is provided in output tubes 48 and 49, a decrease in outputpressure being experienced by the output tube away from which thelaminar stream is deflected, while a corresponding pressure increase isexperienced by the output tube toward which the laminar stream isdeflected. As discussed above, a control stream can be introduced toboth control ports 24 to cause stream deflection in an amountproportional to the difference between the applied control pressures.For certain applications, it is desirable to use a differential outputconfiguration such as provided by the device of FIG. 9, while for otherpurposes a single output configuration is preferable, as in FIG. 7. Forsome purposes, a single output may be offset from the longitudinaldevice axis. In the case of an offset output tube configuration, theamplifier gain will be of a sense dependent upon the direction ofoffset. The control pressure applied to ports 24 can be both positiveand negative and proportional amplification can be provided with eithersense of control pressure as seen from FIG. 10.

The invention in its digital mode of operation can be embodied in avariety of logical configurations to suit particular operatingrequirements. Referring to FIG. 1 1, there is shown a flip flopcomprised of two fluid devices and constructed according to theinvention. First and second fluid devices 50 and 52 are provided, eachhaving its output tube coupled to a control tube of the opposite device.More particularly, output tube 54 is coupled to control tube 56 ofdevice 52, while output tube 58 is coupled to control tube 60 of device50. The supply tubes 62 and 64 are connected to a common source ofsupply pressure. A second control tube 66 of device 50 is coupled to asource of control signalsto provide a SET input, while control tube 68of device 52 is coupled to a source of control signals to provide aRESET input. It will be appreciated that the fluid flip flop circuitexhibits two bistable states, one wherein output A is at a higherpressure level than output B, and vice versa. Once a given bistablestate is established, the device will remain in that state untilswitched to the opposite state by energization of an appropriate SET orRESET control jet. In operation, with a laminar fluid stream flowingfrom supply tubes 62 and 64 and a control stream applied via controltube 66, the pressure in output tube 54 will drop due to the transitionfrom laminar to turbulent flow according to the invention, resulting ina relatively higher pressure level by reason of the laminar flow of theinput stream through the interaction zone of device 52, and this higherpressure flow is coupled from output tube 58 to control tube 60 ofdevice 50 to maintain output A in its low level state even after the SETcontrol signal is removed. When, however, a RESET control signal isapplied to control tube 68, causing the transition from laminar toturbulent flow in device 52, the output pressure in output tube 58markedly drops to provide a relatively lower pressure output B. The dropin pressure in collector tube 58 also causes a corresponding drop inpressure in control tube 60, causing the turbulent flow therein torevert to a laminar condition, with consequent increase in the outputpressure in tube 54. The higher pressure flow in tube 54 is coupledtocontrol tube 56 to maintain device 52 in its low level state afterremoval of the RESET control signal. The invention as embodied in an ANDgate is illustrated in FIG. 12 and includes four fluid devices, eachconstructed as described hereinabove and each having a respective supplytube 70, 72, 74 and 76 coupled to a common source of supply fluid. The

i respective output tubes 78, 80, 82 and 84 of the fluid devices arecoupled to respective control tubes 86 of a fluid device 88, thecollector 90 of which provides the gate output. The supply tube 92 ofdevice 88 is also coupled to the common source of supply fluid. Acontrol tube 94 of respective devices is coupled to respective inputports labeled C, D, E and F. In opera tion, a relatively higher pressureoutput will be provided at output tube 90 when control streams areapplied to all four input tubes, while the output will be at relativelylower pressure for all other input conditions. With control streamssupplied to the four input tubes C, D, E and F, the respective fluiddevices will switch to the turbulent state wherein a lower pressureoutput stream is provided. The four control tubes 86 of device 88 aretherefore essentially inactive with the result that the output pressurein output tube 90 is at a relatively higher level. With the removal ofone or more of the input control streams, those devices for which thecontrol stream is removed will revert to a condition of laminar flow,according to the invention, causing a higher pressure output to appearat the output tube of the aforesaid device, which will energize selectedones of control tubes 86, which, in turn, will cause device 88 to revertto turbulent flow, causing a decrease in pressure in output tube 90. Inthis manner a first digital output state is provided in the presence ofall four input control streams, and a second digital output state isprovided for all other input conditions, thereby implementing thelogical AND function.

Various modifications and implementations will occur to those versed inthe art and it is not intended to limit the invention by what has beenparticularly shown and described.

We claim:

A pure fluid device comprising:

a confined interaction chamber having top and bottom walls and a pair ofside walls;

an input passage having an orifice communicating with one end of saidinteraction chamber and adapted to establish and maintain a fluid streamin laminar flow through said chamber;

a control passage having an orifice communicating with said chamber andadapted to introduce a low energy control stream into said chamber;

a shielded region contiguous with said interaction chamber and vented tothe working atmosphere; and

an output passage having an orifice disposed at the downstream end ofsaid shielded region;

said output passage being operative to provide a predetermined outputpressure in response to a laminar stream received from said inputpassage in the absence of a control stream, and to provide apredetermined different output pressure in the presence of a controlstream;

said confined interaction chamber including a confined region having topand bottom walls substantially parallel and coplanar with said inputpassage, and substantially parallel side walls outwardly disposed fromsaid input passage, said control passage communicating with saidconfined region; and

a shaped region disposed downstream of said confined region andcontiguous therewith, said shaped region having top and bottom wallsdisposed outwardly of the respective top and bottom walls of saidconfined region, and means for providing recirculation of said fluidstream within said shaped region in the presence of a control stream toachieve rapid switching from one binary state to another;

said recirculation means including a channel formed in the top andbottom walls of said shaped region and extending parallel to the axisthereof; and

a rib disposed at the downstream end of each of said channels across thewidth thereof and extending inwardly by an amount to permit unobstructedflow of said laminar stream from said input passage in the absence of acontrol stream and to engage a portion of said laminar stream in thepresence of said control stream.

2. A pure fluid device according to claim 1 wherein said channels areeach of a width substantially equal to the separation between the sidewalls of said confined region.

3. A pure fluid device comprising:

a confined interaction chamber including a confined region having topand bottom walls and a pair of side walls, and a shaped region disposeddownstream of said confined region and contiguous therewith; said shapedregion having top and bottom walls disposed outwardly of the respectivetop and bottom walls of said confined region, and means disposed at thedownstream end of said shaped region for providing recirculation of saidfluid stream within said shaped region in the presence of a controlstream to achieve rapid switching from one binary state to another;

an input passage having an orifice communicating with one end of saidinteraction chamber and adapted to establish and maintain a fluid streamin laminar flow through said chamber;

a control passage having an orifice communicating with one of said sidewalls of said chamber and adapted to introduce a low energy controlstream into said chamber;

said top and bottom walls of said confined region being substantiallyparallel and coplanar with said input passage, and said side walls beingsubstantially parallel and outwardly disposed from said input passage;

a shielded region contiguous with said interaction chamber and havingside walls outwardly disposed from said input passage and top and bottomsurfaces fully vented to the working atmosphere; and

an output passage having an orifice disposed at the downstream end ofsaid shielded region;

said output passage being operative to provide a predetermined outputpressure in response to a laminar stream received from said inputpassage in the absence of a control stream, and to provide apredetermined different output pressure in the presence of a controlstream.

4. A pure fluid device according to claim 3 wherein said recirculationmeans includes an obstruction disposed in said shaped region in anoperative position to permit passage of a laminar stream from said inputpassage in the absence of a control stream and to engage a portion ofsaid laminar stream in the presence of a control stream.

5. A pure fluid device according to claim 3 wherein said recirculationmeans includes a wall disposed at the downstream end of said shapedregion and transversely thereacross;

an aperture formed in said wall in alignment with the orifice of saidinput passage; and

means for venting said shaped region.

6. A pure fluid device according to claim 3 wherein said recirculationmeans includes a channel formed in the top and bottom walls of saidshaped region and extending parallel to the axis thereof; and

an obstructing element disposed at the downstream end of each of saidchannels across the width thereof and extending inwardly by an amount topermit unobstructed flow of said laminar stream from said input passagein the absence of a control stream and to engage a portion of saidlaminar stream in the presence of said control stream.

7. A pure fluid device according to claim 3 wherein said recirculationmeans includes an obstructing element disposed at the downstream end ofsaid shaped region across the width thereof and extending inwardly by anamount to permit unobstructed flow of said laminar stream from saidinput passage in the absence of a control stream and to engage a portionof said laminar stream in the presence of said control stream.

8. A pure fluid device according to claim 3 wherein said confined regionincludes one or more vents communicating between the input end of saidconfined region adjacent said input passage and the working atmosphere.

2. A pure fluid device according to claim 1 wherein said channels areeach of a width substantially equal to the separation between the sidewalls of said confined region.
 3. A pure fluid device comprising: aconfined interaction chamber including a confined region having top andbottom walls and a pair of side walls, and a shaped region disposeddownstream of said confined region and contiguous therewith; said shapedregion having top and bottom walls disposed outwardly of the respectivetop and bottom walls of said confined region, and means disposed at thedownstream end of said shaped region for providing recirculation of saidfluid stream within said shaped region in the presence of a controlstream to achieve rapid switching from one binary state to another; aninput passage having an orifice communicating with one end of saidinteraction chamber and adapted to establish and maintain a fluid streamin laminar flow through said chamber; a control passage having anorifice communicating with one of said side walls of said chamber andadapted to introduce a low energy control stream into said chamber; saidtop and bottom walls of said confined region being substantiallyparallel and coplanar with said input passage, and said side walls beingsubstantially parallel and outwardly disposed from said input passage; ashielded region contiguous with said interaction chamber and having sidewalls outwardly disposed from said input passage and top and bottomsurfaces fully vented to the working atmosphere; and an output passagehaving an orifice disposed at the downstream end of said shieldedregion; said output passage being operative to provide a predeterminedoutput pressure in response to a laminar stream received from said inputpassage in the absence of a control stream, and to provide apredetermined different output pressure in the presence of a controlstream.
 4. A pure fluid device according to claim 3 wherein saidrecirculation means includes an obstruction disposed in said shapedregion in an operative position to permit passage of a laminar streamfrom said input passage in the absence of a control stream and to engagea portion of said laminar stream in the presence of a control stream. 5.A pure fluid device according to claim 3 wherein said recirculationmeans includes a wall disposed at the downstream end of said shapedregion and transversely thereacross; an aperture formed in said wall inalignment with the orifice of said input passage; and means for ventingsaid shaped region.
 6. A pure fluid device according to claim 3 whereinsaid recirculation means includes a channel formed in the top and bottomwalls of said shaped region and extending parallel to the axis thereof;and an obstructing element disposed at the downstream end of each ofsaid channels across the width thereof and extending inwardly by anamount to permit unobstructed flow of said laminar stream from saidinput passage in the absence of a control stream and to engage a portionof said laminar stream in the presence of said control stream.
 7. A purefluid device according to claim 3 wherein said recirculation meansincludes an obstructing element disposed at the downstream end of saidshaped region across the width thereof and extending inwardly by anamount to permit unobstructed flow of said laminar stream from saidinput passage in the absence of a control stream and to engage a portionof said laminar stream in the presence of said control stream.
 8. A purefluid device according to claim 3 wherein said confined region includesone or more vents communicating between the input end of said confinedregion adjacent said input passage and the working atmosphere.